<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="js/v2.6.10/vue.js" type="text/javascript"></script>
		<script src="https://cdn.jsdelivr.net/npm/axios@0.12.0/dist/axios.min.js"></script>
		<script src="https://cdn.jsdelivr.net/npm/lodash@4.13.1/lodash.min.js"></script>

	</head>
	<body>
		<div id="watch-example">
			<p>
				Ask a yes/no question:
				<input v-model="question">
			</p>
			<p>{{ answer }}</p>
		</div>
		<script>
			var watchExampleVM = new Vue({
				el: '#watch-example',
				data: {
					question: '',
					answer: 'I cannot give you an answer until you ask a question!'
				},
				watch: {
					// 如果 `question` 发生改变，这个函数就会运行
					question: function(newQuestion, oldQuestion) {
						this.answer = 'Waiting for you to stop typing...'
						this.debouncedGetAnswer()
					}
				},
				created: function() {
					// `_.debounce` 是一个通过 Lodash 限制操作频率的函数。
					// 在这个例子中，我们希望限制访问 yesno.wtf/api 的频率
					// AJAX 请求直到用户输入完毕才会发出。想要了解更多关于
					// `_.debounce` 函数 (及其近亲 `_.throttle`) 的知识，
					// 请参考：https://lodash.com/docs#debounce
					this.debouncedGetAnswer = _.debounce(this.getAnswer, 500)
				},
				methods: {
					getAnswer: function() {
						if (this.question.indexOf('?') === -1) {
							this.answer = 'Questions usually contain a question mark. ;-)'
							return
						}
						this.answer = 'Thinking...'
						var vm = this
						axios.get('https://yesno.wtf/api')
							.then(function(response) {
								vm.answer = _.capitalize(response.data.answer)
							})
							.catch(function(error) {
								vm.answer = 'Error! Could not reach the API. ' + error
							})
					}
				}
			})
		</script>
	</body>
</html>